An Australian slang term used to indicate another person is soft, easily upset, or just a plain pussy.

Joe: I'm in so much pain right now, I've got such a bad bruise on my knee.
Bob: *Looks at Joe's Knee* You call that a bruise, don't be such a sook, my dick has had bigger bruises on it than that.
John: Yeah Joe you fucking pussy, don't be such a sook.